The invention relates to a medical connector, to an extracorporeal blood treatment apparatus comprising the medical connector, and to a dialysis machine provided with the medical connector. In particular the medical connector can be advantageously used for connecting a fluid transport line (for example a transport line of a fresh or used dialysis fluid) to a fluid access port (inlet or outlet) of a device for extracorporeal blood treatment of the semipermeable membrane type, such as for example a dialyser.
Specifically, though not exclusively, the present invention can be usefully applied for removably connecting the dialysate transport line of a dialysis monitor to a dialysate port of a semipermeable membrane dialyser or to a counter-connector connected to a fluid transport line arranged internally of a cabinet of a dialysis machine.
The prior art comprises various types of semipermeable membrane (dialysis filters) dialysers, which generally each define a blood chamber and a dialysate chamber which are separated from one another by a semipermeable membrane, for example of the hollow bundle type. Each dialyser is usually provided with two blood ports, one for blood inlet and the other for blood outlet, and two dialysate ports, one for the dialysate inlet and the other for the dialysate outlet. To begin the dialysis treatment, the two blood ports are connected to the arterial line and the venous line of an extracorporeal blood circuit, while the dialysate ports are connected to the supply line and the discharge line of the dialysate circuit controlled by the dialysis monitor. The dialysis monitor comprises actuators and sensors which control the correct progress of the dialysis treatment. The monitor for dialysis monitors that the fresh dialysate has the desired characteristics (in particular the temperature and the chemical composition) and that the patient's fluid balance respects a desired weight loss. Usually the supply line and the discharge line of the dialysate circuit each comprise a flexible tube which exits from a front panel of the dialysis monitor cabinet and which terminates with a connector configured for sealed removable coupling with the two dialysate ports of the dialyser. With the aim of readying the dialysis apparatus for the treatment, the operator must connect the dialysate circuit to the membrane dialyser: to this the operator manually takes the flexible tubes and couples the terminal connector with the dialysate port of the dialyser.
The dialysis machine is normally subjected to various procedures beyond the treatment itself, in which the dialysis fluid circuit is not connected to the membrane dialyser. These procedures can comprise, for example, washing and disinfection of the dialysis circuit, in which an operative fluid (chemical disinfectant, heated water, washing fluid, etc.) is placed in circulation along the dialysis fluid circuit. To enable complete circulation in all the circuit, the supply line and the discharge line of the dialysate circuit are connected in series to one another by a bypass block line arranged internally of the cabinet and provided at opposite ends thereof with two counter-connectors arranged on the front panel. The counter-connectors are coupled with the two connectors arranged at the ends of the two flexible tubes which form the end parts of the dialysate discharge.
A problem of dialysis machines of known type is the incorrect coupling of the terminal connectors of the dialysate circuit with the dialysate ports of the membrane dialyser or with the counter-connectors of the bypass block line. The incorrect coupling can lead to various drawbacks, in particular damage to parts of the dialysis apparatus, such as for example the detachment of tubes in the dialysate circuit or the breakage of elements (for example the pressure sensors of the dialysate circuit), or the loss of fluid in the incorrectly-coupled zone.
The prior art comprises various systems for verifying correct coupling of two parts of a medical fluid circuit.
Patent publication No. US 2007/0075003 describes a connector for connecting a dialysate port of a dialyser to a dialysate transport line, in which the blockage is realised by means of an undercut and an elastic element, such that it is audible.
U.S. Pat. No. 5,591,143 describes a luer-type connector provided with a coloured platelet which moves according to whether the connection has been made correctly or not.
U.S. Pat. No. 4,294,250 describes a luer connector provided with visual means for indicating that the connection has been made correctly.
Patent publication No. US 2002/0133136 describes a connector provided with visible means which enable determination of whether a positive blockage of the connection has been obtained or not.
Patent publication No. US 2003/0184090 illustrates a luer connector which reaches an engagement position with a click effect which produces a perceptible signal, in particular tactile and audible.
Patent publication No. WO 2005/068010 describes an adaptor provided with two tabs which enable a visual indication to be given of correct insertion of the adaptor internally of a catheter.
Patent No. EP 635669 illustrates a device for connecting a user to a source of medical gas, in which there are means for indicating a position of a connecting element in a connection box connected to the source. The indicator means can comprise two different colour surfaces which are visible through a window in two different positions, respectively parked and work positions, of the connecting element.
U.S. Pat. No. 6,676,652 describes an adapter for a catheter provided with a mobile arm forming an angle with the adapter body when the connecting mechanism is in the open position, while it is parallel to the adapter body when the catheter is engaged.
Patent publication no. EP 856332 describes an adapter for mounting a fluid transport device with a catheter tube, in which the bolt having an elliptic transversal section is rotatable with respect to the adapter body, also having an elliptic transversal section. The long axis and short axis of the bolt are aligned with the respective long and short axes of the adapter body in the locking position, and with the respective shot and long axes of the adapter body in the insertion position, thus providing a visual and tactile indication of the effective operative position of the bolt. Further, a lens provides an enlarged image of a recess which receives an end of the catheter in order to display the correct placing of the catheter.
Patent publication no. US 2006/0122559 describes a valve which can take on three positions. In an open position, an opening is aligned and in sealed fluid communication with an aspiration port. In an introduction position, the opening is aligned and in sealed fluid communication with an introduction port. In a closed position, there is no communication between the opening and the two above-mentioned ports. Visual evidence arranged on the external surface of the casing provide the indication of the effective position of the opening. The visual evidence can be a raised surface, a depression, a mechanical tooth, a light-emitting surface.
Patent publication no. US 2005/0197646 shows various embodiments of pairs of connectors for medical fluids, in which each pair of connectors is provided with feedback characteristics of audible, visual and tactile type which indicate that the coupling between the connectors has been completed.